PushTableWriteThroughUnion.java
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.sql.planner.iterative.rule;
import com.facebook.presto.Session;
import com.facebook.presto.matching.Capture;
import com.facebook.presto.matching.Captures;
import com.facebook.presto.matching.Pattern;
import com.facebook.presto.spi.WarningCollector;
import com.facebook.presto.spi.plan.PlanNode;
import com.facebook.presto.spi.plan.TableWriterNode;
import com.facebook.presto.spi.plan.UnionNode;
import com.facebook.presto.spi.relation.VariableReferenceExpression;
import com.facebook.presto.sql.planner.iterative.Rule;
import com.facebook.presto.sql.planner.optimizations.SymbolMapper;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ListMultimap;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import static com.facebook.presto.SystemSessionProperties.isPushTableWriteThroughUnion;
import static com.facebook.presto.matching.Capture.newCapture;
import static com.facebook.presto.sql.planner.optimizations.SetOperationNodeUtils.fromListMultimap;
import static com.facebook.presto.sql.planner.plan.Patterns.source;
import static com.facebook.presto.sql.planner.plan.Patterns.tableWriterNode;
import static com.facebook.presto.sql.planner.plan.Patterns.union;
import static com.google.common.collect.ImmutableMap.toImmutableMap;
public class PushTableWriteThroughUnion
implements Rule<TableWriterNode>
{
private static final Capture<UnionNode> CHILD = newCapture();
private static final Pattern<TableWriterNode> PATTERN = tableWriterNode()
// The primary incentive of this optimizer is to increase the parallelism for table
// write. For a table with partitioning scheme, parallelism for table writing is
// guaranteed regardless of this optimizer. The level of local parallelism will be
// determined by LocalExecutionPlanner separately, and shouldn't be a concern of
// this optimizer.
.matching(tableWriter -> !tableWriter.isSingleWriterPerPartitionRequired())
.with(source().matching(union().capturedAs(CHILD)));
@Override
public Pattern<TableWriterNode> getPattern()
{
return PATTERN;
}
@Override
public boolean isEnabled(Session session)
{
return isPushTableWriteThroughUnion(session);
}
@Override
public Result apply(TableWriterNode writerNode, Captures captures, Context context)
{
UnionNode unionNode = captures.get(CHILD);
ImmutableList.Builder<PlanNode> rewrittenSources = ImmutableList.builder();
List<Map<VariableReferenceExpression, VariableReferenceExpression>> sourceMappings = new ArrayList<>();
for (int source = 0; source < unionNode.getSources().size(); source++) {
rewrittenSources.add(rewriteSource(writerNode, unionNode, source, sourceMappings, context));
}
ImmutableListMultimap.Builder<VariableReferenceExpression, VariableReferenceExpression> unionMappings = ImmutableListMultimap.builder();
sourceMappings.forEach(mappings -> mappings.forEach(unionMappings::put));
ListMultimap<VariableReferenceExpression, VariableReferenceExpression> mappings = unionMappings.build();
return Result.ofPlanNode(
new UnionNode(
writerNode.getSourceLocation(),
context.getIdAllocator().getNextId(),
rewrittenSources.build(),
ImmutableList.copyOf(mappings.keySet()),
fromListMultimap(mappings)));
}
private static TableWriterNode rewriteSource(
TableWriterNode writerNode,
UnionNode unionNode,
int source,
List<Map<VariableReferenceExpression, VariableReferenceExpression>> sourceMappings,
Context context)
{
Map<VariableReferenceExpression, VariableReferenceExpression> inputMappings = getInputVariableMapping(unionNode, source);
ImmutableMap.Builder<VariableReferenceExpression, VariableReferenceExpression> mappings = ImmutableMap.builder();
mappings.putAll(inputMappings);
ImmutableMap.Builder<VariableReferenceExpression, VariableReferenceExpression> outputMappings = ImmutableMap.builder();
for (VariableReferenceExpression outputVariable : writerNode.getOutputVariables()) {
if (inputMappings.containsKey(outputVariable)) {
outputMappings.put(outputVariable, inputMappings.get(outputVariable));
}
else {
VariableReferenceExpression newVariable = context.getVariableAllocator().newVariable(outputVariable);
outputMappings.put(outputVariable, newVariable);
mappings.put(outputVariable, newVariable);
}
}
sourceMappings.add(outputMappings.build());
SymbolMapper symbolMapper = new SymbolMapper(mappings.build(), WarningCollector.NOOP);
return symbolMapper.map(writerNode, unionNode.getSources().get(source), context.getIdAllocator().getNextId());
}
private static Map<VariableReferenceExpression, VariableReferenceExpression> getInputVariableMapping(UnionNode node, int source)
{
return node.getOutputVariables().stream().collect(toImmutableMap(key -> key, key -> node.getVariableMapping().get(key).get(source)));
}
}